It is working with its client Nishimatsu Construction on the design of the Cross Island Line (CRL), which is expected to open in 2030. CRL will be Singapore's longest fully underground line at more than 50 kilometres and is expected to carry over 600,000 commuters each a day.
Cowi’s package of work in collaboration with Nishimatsu includes a 2.9km bored tunnel, 300m of cut and cover tunnels and a two-storey facility building with five levels of basement to provide electrical and mechanical services.
A 12.6m-diameter tunnel boring machine (TBM) will be used to construct the two-track tunnel. The cut and cover tunnels will extend to a depth of 45m and the bored tunnel depth will vary from almost 50m underground at its deepest to less than 12m cover at its shallowest.
Vince Goh, managing director for Cowi in Singapore, said: “This project involves a number of exciting technical challenges other than the large diameter tunnel itself. Among others, the tunnel will go underneath a military airport with sensitive fibre reinforced pipe (FRP), runway, taxiway, apron, airport structures which increase limitation in ground movement during both bored and mined tunnelling operation. Moreover, any TBM cutterhead intervention beneath the airbase will need to be pre-planned and in hyperbaric environment due to the depth.”
Multiple closely spaced adits for future underground infrastructure are also part of the challenge, he said. The tunnel will also go under public roads and will under cross the Sungei Serangoon vehicular bridge and Kallang-Paya Lebar Expressway viaduct.”
Construction works are expected to start in June this year.